How vascular properties affect the BOLD contrast across cortical depth.

Abstract

In the current study, we quantify vascular properties in relation to laminar BOLD fMRI signals for differently sized vascular compartments across cortical depth. Using hypercapnic and hyperoxic breathing conditions, while measuring from macro- and micro-vascular compartments, we estimate effects of dilation capacity, theoretical maximum signal intensity, and relative change in cerebral blood volume on laminar BOLD contrasts. We show that enlarged signals for larger pial veins are mainly caused by their capacity for dilation. BOLD signal differences between macro- and micro-vascular compartments are not likely caused by differences in theoretical maximum signal intensity, or relative changes in cerebral blood volume.